The invention relates to compositions comprising at least one Boswellia extract, or at least one boswellic acid or derivative thereof. The compositions are suitable for application to the skin or hair.
It has long been known that extracts of the Boswellia family of plants including Boswellia Serrata can produce a soothing effect to irritated skin and that this activity is due to the terpenoid compounds grouped under the general name boswellic acids. The different boswellic acids share the same basic pentacyclic triterpene (steroid-like) structure but differ in their side groupings.
EP-A-755.940 relates to a novel fraction and a process for the isolation of said fraction comprising a mixture of specified boswellic acids from the gum resin of Boswellia Serrata. The fraction is stated to exhibit anti-inflammatory, anti-arthritic and antiulcerogenic activity.
Typical extracts of Boswellia plants are solids or powders with a wide melting rangexe2x80x94normally above 80xc2x0 C. To allow for easy incorporation into compositions which are suitable for use on the skin or hair, an extract of Boswellia, containing the boswellic acids, or boswellic acids or derivatives thereof themselves, need to be dissolved or dispersed in a suitable carrier. Although they can be dissolved in solvents such as methanol, ethyl acetate, acetone and the like, these solvents are not suitable for use in typical skin and hair care formulations because of their aggressive solvent action on the skin and hair, and/or because of their high volatility and/or strong odour.
Ingredients which are commonly used in skin care or hair care formulations, such as glycerine, sorbitol, mineral oil, cyclomethicone, dimethicone and petrolatum are not suitable solvents or carriers for Boswellia extracts or boswellic acids or derivatives thereof as they are either too polar or not sufficiently polar.
Alkalies can produce aqueous solutions of boswellic acids by forming the respective salts. However, prolonged skin or hair contact by alkaline products (e.g. with a pH greater than 8.5) is not recommended, especially for sensitive skin or scalp, or for damaged hair.
We have now surprisingly found that a specified group of fatty alcohols or fatty acids, or derivatives, or mixtures thereof, are suitable carriers for dissolving and/or dispersing at least one Boswellia extract, or at least one boswellic acid or derivative thereof. Further, the carrier aids the incorporation of the extract, or acid, into compositions suitable for use on the skin or hair and improves the stability of said compositions containing the extract, or acid.
According to a first aspect of the invention, there is provided a composition suitable for use on the skin or hair comprising;
a) at least one extract of a Boswellia plant, or at least one boswellic acid or derivative thereof; and
b) a carrier selected from the group consisting of branched fatty alcohols containing 8 to 32 carbon atoms, branched fatty acids containing 8 to 32 carbon atoms, unsaturated fatty alcohols containing 12 to 24 carbon atoms, unsaturated fatty acids containing 12 to 24 carbon atoms, and derivatives of said branched fatty alcohols, said branched fatty acids, said unsaturated fatty alcohols and said unsaturated fatty acids, or mixtures thereof.
According to a second aspect of the present invention, there is provided a method of preparing a composition suitable for application to the skin or hair comprising mixing a composition comprising;
a) at least one extract of a Boswellia plant, or at least one boswellic acid or derivative thereof; and
b) a carrier selected from the group consisting of branched fatty alcohols containing 8 to 32 carbon atoms, branched fatty acids containing 8 to 32 carbon atoms, unsaturated fatty alcohols containing 12 to 24 carbon atoms, unsaturated fatty acids containing 12 to 24 carbon atoms, and derivatives of said branched fatty alcohols, said branched fatty acids, said unsaturated fatty alcohols and said unsaturated fatty acids, or mixtures thereof
with at least one cosmetically or pharmaceutically acceptable ingredient.
According to a third aspect of the present invention, there is provided a use of a composition comprising;
a) at least one extract of a Boswellia plant, or at least one boswellic acid or derivative thereof; and
b) a carrier selected from the group consisting of branched fatty alcohols containing 8 to 32 carbon atoms, branched fatty acids containing 8 to 32 carbon atoms, unsaturated fatty alcohols containing 12 to 24 carbon atoms, unsaturated fatty acids containing 12 to 24 carbon atoms, and derivatives of said branched fatty alcohols, said branched fatty acids, said unsaturated fatty alcohols and said unsaturated fatty acids, or mixtures thereof,
for preparing compositions suitable for application to the skin or hair.
The compositions of the invention comprise at least one extract of a Boswellia plant, or at least one boswellic acid or derivative thereof.
The compositions of the present invention suitably comprise a safe and effective amount, preferably from 0.005% to 50% by weight of the composition and more preferably from 0.05% to 25% by weight of the composition of at least one Boswellia extract, or at least one boswellic acid or derivative thereof.
Suitable extracts for use herein may be derived from the following Boswellia plants including Boswellia Cartenii, Boswellia Frereana, Boswellia Bhau-dajaina, Boswellia Serrata and Boswellia Thurifera. The preferred plants from which extracts are derived are Boswellia Serrata.
The extracts derived from Boswellia plants can comprise gums, oleo-gums, resins, essential oils and residues, or mixtures thereof. Preferred extracts for use herein are gums.
The Boswellia gum extract useful herein comprises a mixture of active triterpenoid compounds more commonly known as boswellic acids. All boswellic acids have a pentacyclic structure based on 12-ursen-24-oic acid with differing substituents. Many individual boswellic acid compounds have been isolated from the Boswellia extract including xcex1- and xcex2-boswellic acids and derivatives thereof. Of these, xcex2-boswellic acid and derivatives thereof are thought to be the active components.
A typical extract comprising Boswellia Serrata gum resin will comprise greater than 50% by weight boswellic acids and often more than 60% by weight boswellic acids.
A typical extract of a Boswellia plant suitable for use herein comprises a mixture of boswellic acids comprising at least one of 3a-hydroxyurs-12-ene-24-oic acid, 3a-acetoxyurs-12-ene-24-oic acid, 3a-hydroxyurs-12-ene-11-keto-24-oic acid and 3a-hydroxyurs-9,12-dien-24-oic acid.
Boswellia extracts suitable for use herein are commercially available for example from Quest International, Kent, UK.
The compositions of the invention also comprise a carrier for the at least one extract of a Boswellia plant, or the at least one boswellic acid or derivative thereof.
In accordance with the invention, suitable carriers for this purpose are selected from the group consisting of branched fatty alcohols containing 8 to 32 carbon atoms, branched fatty acids containing 8 to 32 carbon atoms, unsaturated fatty alcohols containing 12 to 24 carbon atoms, unsaturated fatty acids containing 12 to 24 carbon atoms, and derivatives of said branched fatty alcohols, said branched fatty acids, said unsaturated fatty alcohols and said unsaturated fatty acids, or mixtures thereof.
The compositions of the present invention typically comprise from 50% to 99.995%, preferably from 75% to 99.95%, and even more preferably from 80% to 95% of a carrier by weight of the composition.
The preferred carriers for use herein are selected from branched fatty alcohols or branched fatty acids containing 8 to 32 carbon atoms, or mixtures thereof, which are liquids at room temperature. Preferably, the branched fatty alcohols and fatty acids are saturated. Saturated compounds generally have good stability against oxidation. More preferred, are saturated, branched fatty alcohols or fatty acids containing from 8 to 20 carbon atoms. Particularly useful branched fatty alcohols and fatty acids herein include isostearyl alcohol, isostearic acid, isocetyl alcohol, isopalmitic acid, octyldodecanol, octyldecanol, hexyldecanol, butyloctanol and ethylhexanol.
Unsaturated fatty alcohols and unsaturated fatty acids, containing 12 to 24 carbon atoms which are liquid at room temperature are also good carriers for Boswellia extracts. However, their presence may be disadvantageous in compositions requiring long term storage because as they are unsaturated, they have the potential to become oxidised and rancid over time. Preferred for use herein are unsaturated fatty alcohols or unsaturated fatty acids containing from 16 to 20 carbon atoms. Particularly useful unsaturated alcohols and unsaturated acids herein include oleyl alcohol, oleic acid, linoleic acid and linolenic acid.
Derivatives of the above described branched, or unsaturated fatty acids and alcohols are also good carriers for the Boswellia extract. Useful derivatives include the following:
(a) Ethoxylated derivatives that are liquid at room temperature. Useful ethoxylated derivatives herein include derivatives of branched fatty alcohols or acids and derivatives of unsaturated fatty alcohols or acids. Preferably, the number of ethylene oxide units per mole of fatty acid or fatty alcohol is in the range 1 to 15 and more preferably is in the range 1 to 10. It is also preferred that the derivative has a calculated HLB (hydrophilic/ lipophilic balance) of less than 15 and preferably in the range 2 to 9.
(b) Esters of the abovementioned branched, or unsaturated fatty acids, the esters being liquid at room temperature. The fatty acids may be esterified with a wide variety of alcohols, including branched or linear, saturated or unsaturated alcohols. Preferably, the fatty acid is esterified with an alcohol containing from 2 to 18 carbon atoms. Preferred esters for use herein are branched or unsaturated fatty acids esterified with a hexitol anhydride. The esters of hexitol anhydrides can be mono-, di- or tri-esters but are preferably mono-esters (i.e. the ratio of acid to hexitol anhydride is 1: 1). A particularly preferred hexitol anhydride from which to prepare an ester is sorbitan. Other preferred esters are monoesters of glycerol and a branched fatty acid (monoglycerides of branched fatty acids). Monoglyceride compositions herein contain at least 80 per cent by weight of a monoglyceride of a single acid. Yet other preferred esters are monoesters of propylene glycol, butylene glycol, hexylene glycol or dipropylene glycol and a branched or an unsaturated fatty acid.
(c) Esters of the branched fatty alcohols or unsaturated fatty alcohols, the esters being liquid at room temperature. The fatty alcohols may be reacted with a wide variety of acids, including branched or linear saturated or unsaturated acids and hydroxy acids such as (xcex1-hydroxy acids or xcex2-hydroxy acids. Preferably, the acid contains from 2 to 18 carbon atoms.
(d) Ethoxylated derivatives of hexitol anhydride esters as defined in (b) above. The degree of ethoxylation is preferably from 1 to 15 ethylene oxide, units per mole of hexitol anhydride ester and the ethoxylated ester is liquid at room temperature.
(e) Ethoxylated derivatives of monoglycerides as defined in (b) above. The degree of ethoxylation is preferably from 1 to 15 ethylene oxide units per mole of monoglyceride and the ethoxylated monoglyceride is liquid at room temperature.
Generally, the carriers used in the compositions of the invention are liquid at room temperature. However, it is not essential that the carrier should be completely free from solid matter. Since many available fatty alcohols and fatty acids comprise mixtures of alcohols or acids, certain isomers can be present as solid matter in the mixture. The presence of such solid matter is not detrimental to the use of a particular carrier, provided that the carrier is fluid at room temperature. For the purposes of assessing fluidity in relation to this invention a temperature of 23xc2x0 C. is assumed for xe2x80x9croom temperaturexe2x80x9d.
The carriers used in the compositions of the invention are capable of dispersing or dissolving the Boswellia extracts or boswellic acids or derivatives thereof. It is not essential that the extract or acid be completely soluble in the carrier, provided that the mixture of extract or acid and carrier can be incorporated into skin care or hair care products to produce a stable composition.
The carrier of the present invention may also include other exicipients conventionally added to compositions suitable for application to the skin or hair such as, silicones, solvents such as water, emollients, or emulsifiers for example.
Optionally, the compositions herein may comprise conventional ingredients normally present in compositions for application to the skin or hair. Non-limiting examples of such ingredients include alkanolamide surfactants, alkyl polyglucose derivatives, alkyl ether sulphate surfactants, allantoin, aloe barbadensis mil (aloe vera linne), xcex1-hydroxycarboxylic acids, aluminium chlorhydrate and its derivatives, aluminium salts, amide derivatives, amino acids, amphoteric surfactants, ascorbic acid and its salts, bentonite and hectorite, benzyl alcohol, bisabolol, butane propellants, carboxy vinyl polymer water soluble salts, carboxy methylcellulose, carrageenan, cetrimonium salts, cholesterol, cocamidopropyl betaine, depilatories, dihydroxyacetone, dimethyl ether, ethanol, fatty acids, fatty acid citrate esters, fatty alcohols, fragrance ingredients, glucose esters of higher fatty acids, glycerin, glyceryl stearates, glycols, guar gum, gum arabic, hyaluronic acid, hydroxybenzoic acids, hydroquinone, isopropyl alcohol, kojic acid, lanolin, lauryl betaine, lipids extracted from the biomass of microorganisms, yeasts, moulds and bacteria, liposomes, liquorice (glycyrrhiza glabra) and its components (glycyrrhetinic acid, glycyrrhizic acid, etc.), low molecular weight acidic mucopolysaccharides and their salts, low molecular weight humectant components, magnesium aluminium silicate, methacrylate polymers, mineral oils, mineral powders, natural or synthetic amino acid with protein or peptide bond, natural moisturing factor ingredients eg lactic acid. non-volatile silicones, oil agent(s), oil matter, oligosaccharide(s), organic acids, pantothenic acid and its derivatives, petroleum jelly, phospholipid, polysaccharides eg locust bean gum, polyvinyl alcohol, polypeptides, proteins, piroctone olamine, quaternised silicone derivatives, raffinose, saponins, sodium chloride, sodium cocoyl isethionate, sodium hyaluronate, sources of linoleic acid, sterols, sterol esters, sucrose, sugar esters of higher fatty acids, sunscreens, surfactants, talc, tea tree oil (Melaleuca spp.), thioglycolic acid and its derivatives, titanium dioxide, tocopherol and esters thereof, triclosan, mono- or di- or triglycerides, vegetable oils, vitamins and analogues, volatile silicone fluids, water, water soluble moisture-retaining agents, water soluble polymers, waxes, zinc oxide, zinc pyrithione.
The compositions of the present invention may be used in a wide range of products suitable for use on, or application to, the skin or hair particularly, but not exclusively, cosmetic compositions. Such products may be formulated in various product forms such as lotions, creams, gels, sticks, solutions, aerosols, solid soaps or liquid cleansers. Thus, in a further aspect, the present invention provides a product for application to the skin or hair comprising a composition in accordance with the invention. The term skin as used herein, means any outer surface of the body including the nails.
When products comprising a composition in accordance with the invention are prepared, the composition of the invention can be separately prepared and added to the other ingredients of the desired product, or the compositions of the invention can be formed during the manufacture of the product.